1. Field of the Invention
The invention relates to valve components and manifolding controlling the air intake and combustion gas exhaust flows of internal combustion engines.
2. Description of Prior Art
In my earlier cross-referenced copending patent, the exhaust and intake lobes of the camshaft were combined to form a single broad lobe cam bearing upon a single popper valve controlling both the exhaust and intake flows through a common valve port. The advantage of such a system is that it permits a fully open valve duration equal to the degree of lobe separation which in todays high performance engine is about 110.degree. or a corresponding 220.degree. of engine crank rotation. The ability of this type of system to complete the exhaust stroke with the valve in the fully open position at the end of 55.degree. degrees of camshaft rotation and to begin the induction stroke with the valve in the same fully open position for the remaining 55.degree. of camshaft rotation greatly reduces the engine piston pumping work and improves the engine volumetric efficiency. In the present invention the efficiency of the separation of the exhaust and intake streams is improved by changing the configuration of the diffuser such that its flow axis is aligned with the flow axis of the exhaust pipe. This is somewhat similar to Birman's U.S. Pat. No. 2,406,656 in which he aligns diffusers in the exhaust pipe leading to a turbine. However, in this latter instance the flow is entirely within the exhaust circuit and is not in communication with the air induction circuit as in the present invention.
Another feature of the present invention is the addition of a resonance chamber which is positioned adjacent to the exhaust nozzle exit. The resonance chamber responds as a pressure reservoir damping the pulsations and fluctuations occurring in the intervening space between the exhaust nozzle exit and the diffuser inlet during the alternating exhaust and intake strokes of the engine piston. In the present invention no attempt is made to tune the air channel length leading to the resonance chamber as is the case of induction systems designed in accordance with the well understood Helmholtz relationship. The purpose of the resonance chamber in this instance is to limit the lag of flow reversal within the nozzle when the engine piston is at its top-dead-center position of crank rotation at the end of the exhaust stroke and is at the beginning downward stroke of the cycle, with the poppet valve held in the fully open position by the combined-lobe cam.
Another improvement of the present invention is in the fabrication of the injection cup in which the valve seat is formed as an integral part of a single component insert which is press-fit into the valve well in one operation during the engine assembly. By forming the valve seat with the injection cup the component becomes more cost effective in both its manufacture and in its assembly on the engine.
The function of the injection cup is improved by forming the inner cylinder passageway as a conical convergency such that its diffuser action is increased during the engines induction stroke. The outer cylinder passage way is formed as a conical divergency such that its nozzle action is also increased during the induction stroke. Used in the above context, a nozzle is defined as a divergent flow channel in which the fluid velocity is increased and its pressure is decreased. Similarly a diffuser is defined as a convergent flow channel in which the fluid velocity is decreased and its pressure is increased. Hereinafter the terms "nozzle action" and "diffuser action" will pertain to flow phenomena in the present invention by this definition. During the engines exhaust stroke the above flow processes are reversed such that the inner cylinder passageway now reacts as a nozzle and the outer passageway of the injection cup reacts as a diffuser.
By increasing the diffuser action of the injection cups inner passageway an alcohol water mixture or other mixtures injected into the cup are held slightly longer at higher pressures. The heat transferred to the water molecules of the mixture should be sufficiently high such that its quenching effect within the engines combustion chamber is diminished. This is seen as a regenerative process in which a portion of the waste heat of the exhaust gas is returned to the combustion chamber. Ignition of combustible stagnant gases at the heated surfaces of the cup occurs only if a sufficiently large concentration of reactant is present to generate a steady combustion wave. In the flowing system, the heat capacity of the cup and that of the water vapor within the laminar flow of the boundary at the surface or turbulent mixing zone of the inner passageway are considered, it can be seen that the necessary concentrations are not present and that the energy level required to ignite the mixture is too low to cause burning in the valve well. Therefore, combustion does not occur until the mixture is compressed with the air charge at the end of the engine pistons compression stroke at which time it is electrically spark ignited.
When the heat sink capability of the inner cylinder of the injection cup is not sufficiently large enough to maintain the evaporation process at a sufficiently high temperature to prevent excessive quenching during combustion, additional heat transfer to the inner cylinder is achieved by placing vertical fins on its outer surface to extract more heat from the exhaust gases flowing in the outer passageway.
When only indirect injection is used an electrical heater is placed in the fuel injection conduit of the injection cup as an optional feature to promote vaporization. The electrical heater circuit is automatically broken by a timing switch or thermal relay switch after the engine is started and the injection cup has been raised to its operating temperature. When both direct and indirect injection is employed in the engine design, electrical heating is not required.
In the Cross Referenced patents the engine exhaust manifold is located outside of the airchest. In the present invention the exhaust manifold is located inside the airchest. This is contrary to accepted practice where in most instances it is desirable to keep the temperature of the air-charge as low as possible in order to create m higher expansion of the working fluid after combustion. Because of the high volumetric efficiency of the univalve engine which is made possible by the combined-lobe cam, the convective heating of the air-charge by its passing over the heated surface of the exhaust manifold within the airchest is slight. The heated air does not exert as severe a cooling effect upon the steam vapor produced in the injection cup and therefore it is not as readily condensed and its relative quenching effect upon the combustion is diminished. The convective air cooling of the exhaust manifold causes the hot gases flowing in the manifold to contract such that the manifold pressure decreases and thus lowers the pressure at the diffuser exits steadying the flow through the diffuser. The cooling effect can be further increased by placing cooling fins around the exhaust manifold to increase the amount of heat transferred.
In one design of the present invention a water cooling jacket is placed around the exhaust manifold to cause the contraction of the hot gases within.